Ask around at your school and see what others get for babysitting. I would think between $5 and $10 an hour. That's a big responsibility and you'll work hard with toddlers - just ask their mom.

The more you are expected to do, the more you should be paid. If you come over after the kids are asleep you might get paid at the lower end, but if you are expected to feed them a meal, play with them, get them ready for bed, put them to bed, clean up, etc, then you certainly deserve to get $10 an hour.

I have a 15-year-old daughter, and she charges $7-$10 an hour, depending on the situation (how old are the kids, how many kids, how late she has to stay out). Rates can vary a lot by area (e.g., New York, vs. a suburb, vs. rural). You can also charge more if you have done courses in babysitting and can show certification in first aid and CPR.